The formula for calculating the amount of solute needed to prepare a solution of a given concentration is:

$$Molarity = \frac{Moles \ of \ Solute}{Liters \ of \ Solution}$$

Rearranging the formula to solve for moles of solute, we get:

$$Moles \ of \ Solute = Molarity \times Liters \ of \ Solution$$

In this case, we want to prepare 2.5 N H2SO4 and we want to make 1 L of solution. Plugging these values into the formula, we get:

$$Moles \ of \ H2SO4 = 2.5 N \times 1 L = 2.5 \ moles \ H2SO4 $$

Step 2: Calculate the mass of H2SO4 needed.

Step 1: Take the number of moles of solute and multiply it by the molar mass of the solute to get the mass in grams.

The molar mass of H2SO4 is 98.08 g/mol. So, the mass of H2SO4 needed is:

Mass = moles × molar mass

= 2.5 mol × 98.08 g / mol

= 245.2g

Step 3: Prepare the solution.

Pour 245.2g of H2SO4 into a 1-L volumetric flask

Add deionized water to the flask until the total volume reaches 1 L

Swirl the flask gently to mix the solution.

Note: Always add acid to water, never water to acid, to avoid splattering. Wear safety gear, including gloves and eye protection, when handling concentrated acids.